As I said, that is pretty unusual for Anguilla. Yes, if you don't like rough seas and you want to see St. Barts, take the plane!! Going TO St. Barts is almost always rough, much calmer on the way back.
Spent a couple of weeks in February in Captiva. Beautiful house near the beach called the "Absentminded"--go to VRBO. And the village of Captiva is small but absolutely a blast. And the weather versus the Midwest was fantastic....high 70's and low 80's! Easy to get to and nice to vacation in the USA...although we are sailing BVIs in 13 days!!!